The US space agency (Nasa) has cancelled the book intended to challenge the conspiracy theorists who claim the Moon landings were a hoax.

Nasa declined to comment specifically on the reasons for dropping the publication, but it is understood the decision resulted from the bad publicity that followed the announcement of the project.

Criticism that Nasa was displaying poor judgement and a lack of confidence in commissioning the book caused it to abort the project, agency spokesman Bob Jacobs said.

Oberg will still write the book

Nasa had hired aerospace writer Jim Oberg for the job on a fee of $15,000.

He says he will still do the work, although it will now be an unofficial publication with alternative funding.

The book will deliver a point-by-point rebuttal of the theory that the Apollo landings were faked in a movie studio, to convince the world that the US had beaten the Soviets to the Moon.

It will explain why in still and video footage of the landings, no stars can be seen in the Moon sky, why a flag appears to ripple on the atmosphere-free satellite and why shadows fall in strange directions - all "facts", conspiracy theorists say, point to a hoax.

Some commentators had said that in making the Oberg book an official Nasa publication, the agency was actually giving a certain credibility to the hoax theory.